What's wrong with national socialism outside of the emphasis on race, and sometimes on genocide?

You mean other than it also being a totalitarian style system that puts emphasis on subservience of the individual to the state and denounces human rights and democracy in favor of a might makes right ideology where the weak should be under rule of the strong?

Don't get me wrong, there were some good policies like trying to end child labor and rudimentary social security (at least for the 'in-groups'). But ultimately, the militaristic and nationalistic ideologies inherent are terribly dangerous to neighbors. The authoritarian nature is dangerous to the liberty of its own citizens. And it's demands for cultural homogeny and conformity narrow the long-term growth prospects for innovation and future adaptation.